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Research Suggests Improved Accuracy for Cannabis Testing

"Our unique dilute-and-shoot method can separate and quantify delta 8- and 9-THC-COOH."

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Two studies featured today at the 2023 AACC Annual Scientific Meeting & Clinical Lab Expo highlight advances that could boost the accuracy of marijuana tests and provide vital information for addressing the opioid epidemic. The first describes a promising method for determining when urine samples have been tampered with to evade a positive result for marijuana. The second found that more than half of fentanyl samples contained novel psychoactive substances that could heighten the drug's danger.

The legalization of marijuana in many states and the emergence of the fentanyl crisis have underscored the need for accurate and reliable drug tests. As marijuana use becomes more prevalent, researchers are focused on improving the detection methods used for legal, medical, and workforce drug tests. For example, many labs want help identifying when urine samples have been manipulated to avoid a positive result for marijuana.

Deaths from opioid overdoses have been steadily climbing in the U.S. since 2020, in part due to the spread of the powerful narcotic fentanyl. At the same time, there has been a rise in the prevalence of novel psychoactive substances, which are often added to drugs sold as fentanyl to enhance potency. These substances can raise the risk of overdose and death.

"Dilute-and-Shoot" Method Detects Manipulated THC Samples

A scientific team led by Yubo Chai, MD/PhD, at the Mayo Clinic in Rochester, Minnesota, devised a method to counteract the drug-masking effects of common adulterants in marijuana tests. The researchers gathered 5 urine samples positive for both delta 8- and 9-THC-COOH, which are active ingredients of cannabis. They treated them with the adulterant nitrite or strong acid adulterants and found that the compounds quickly degraded both of the ingredients and the internal standard.

The team then implemented a "dilute-and-shoot" workflow that combines a tandem- mass spectrometry method and liquid chromatography separation system. The system can determine whether a urine sample is truly negative or only appears so because it has been degraded by nitrite. The method was further validated with an additional crop of 12 specimens that contained delta 8-THC-COOH, delta 9-THC-COOH, or both.

"Our unique dilute-and-shoot method can separate and quantify delta 8- and 9-THC-COOH," Chai said. "As a result, labs will be able to distinguish between true negative delta 8- and 9-THC-COOH results from specimens adulterated with nitrite, as the latter lack peaks for both the analytes and the internal standard."

Chai noted that their study only tested samples adulterated with sodium nitrite. He calls for further work with samples tainted with other compounds such as peroxide and potassium nitrite.

Study Sheds Light on "Designer" Substances in Fentanyl

In another study, a group led by Gemma Campbell at Aegis Sciences Corp. in Nashville set out to evaluate how common novel psychoactive substances are in fentanyl tests. Studying 200 urine and oral fluid samples gathered from individuals in 30 U.S. states who tested positive for fentanyl, the scientists performed additional testing for designer opioids, benzodiazepines, synthetic marijuana, and other substances.

Strikingly, 117 of the samples (58.5%) tested positive for at least one novel psychoactive substance. Almost 38% of the samples tested positive for xylazine, which possesses opioid-like effects but can't be reversed by naloxone, a life-saving medication that blocks the effects of opioid overdose. Nearly half (47%) of the samples contained other designer opioids, and 8% tested positive for designer benzodiazepines, which can prove deadly when combined with opioids outside of medical settings.

"The timeliest finding as it relates to the danger of today's illicit drug supply was finding xylazine in 38% of the fentanyl samples," said study scientist Andrew Holt, Pharm.D, at Aegis Sciences Corp.

"Depending on where drug testing occurs, an understanding of the other substances present in the illicit drug supply can change the approaches to harm reduction with communities and individuals," he added.

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